Dipole-dipole interaction-induced dense primitive solid-electrolyte interphase for high-power Ah-level anode-free sodium metal batteries.

Abstract

High-energy and resource-abundant anode-free sodium metal batteries suffer from limited lifespan owing to dendrite growth and rapid capacity fading at early stages, particularly at high rate and high capacity. Here we report a preliminary surface-passivation strategy by highly fluorinated electrolyte, instantly forming a dense inorganic-dominant primitive solid-electrolyte interphase. Driven by dipole-dipole interaction, the spontaneously formed solid-electrolyte interphase is sufficiently dense to resist solvent decomposition and moisture attack, meanwhile regulating Na plating/stripping at high current densities and areal capacities up to 8 mA cm^-2 and 5 mAh cm^-2, respectively. The fabricated anode-free batteries demonstrate long-term stability at high cathode loadings (10-15 mg cm^-2) and high rates (1-3 C), even with moisture contained. Impressively, fast-charging Ah-level anode-free pouch cells deliver energy density up to 150 Wh kg^-1 (0.5 C) based on total cell weight, achieving power density as high as 152 W kg^-1 and long lifespan up to 700 cycles at 1 C.